Semiconductor devices such as ICs are often subject to testing. Testing presents many technical challenges in order to adequately verify the operation of the device under test (DUT), and simultaneously to minimize false readings due to the test conditions. Electromagnetic interference is often present in the manufacturing environment, and can result in erroneous test readings. Erroneous readings can lead to the rejection of serviceable devices, or in the failure to detect defective devices. Both problems potentially result in increased costs.
Testing can be a major contributor to the cost of semiconductor device development and manufacturing. Integrated circuits can be tested in various ways. One common test technique is to electrically stimulate one or more ICs on a tester load board, and monitor the electrical response. Typically automated test equipment (ATE) is connected, through the test load board, to external electrical leads on the DUT. The test equipment stimulates the DUT by providing electrical signals to the DUT's input pins and then monitoring the resultant electrical signals provided from the DUT on its output pins. The use of sophisticated and expensive tester load boards necessitates that attention be given to the minimization of damage to the load boards during storage, shipping, and handling, as well as to shielding the load boards from electromagnetic interference during testing.
Load boards used for testing are generally intricate and costly. As the interface between the automatic test equipment (ATE) and the device under test (DUT), the load board typically contains the components required to prepare the DUT for testing, route the test and response signals between the DUT and the ATE, and in some cases to provide additional test capabilities not provided for in the ATE design. There are also load boards designed for the purpose of testing or calibrating the ATE. Load boards are usually customized to a specific device or group of devices. As such, complete, ready-to-use load boards are not normally available off-the-shelf. Accordingly, much design and engineering attention is devoted to designing and fabricating a load board for a particular application. A typical load board has a printed circuit board (PCB) with a test socket for receiving a DUT, as well as an assortment of interconnected components, e.g., ICs, resistors, capacitors, relays, connectors, and so forth, that make up the test circuitry. Load board design takes into consideration many factors such as power supply routing, signal routing, and the avoidance of electrical interference. Electromagnetic interference with, or physical damage to the testing load board can lead to delays and increased expense in the manufacturing process. Due to these and other problems, it would be useful and advantageous to provide improved shielding to tester load boards in order to provide protection from electromagnetic interference and physical damage.